Communication within an interactive two-way broadcast data service network is described in detail in application Ser. No. 07/966,414, filed Oct. 26, 1992 now U.S. Pat. No. 5,388,101 G. Dinkins, entitled "Interactive Nationwide Data Service Communication System For Stationary And Mobile Battery Operated Subscriber Units" which is incorporated herein by reference. In such a system, a local base station repeater cell comprises a central transmitter and data processing site for transmitting digital data to individual low-cost, portable, battery-operated, milliwatt transmitter, subscriber units within a local base station designated area. A plurality of receive only stations, remote receivers, are distributed throughout the local base station designated area and are connected by wire, cable, microwave link, or radio to the local base station repeater cell. The remote receivers process and relay transmitted digital data received from the individual subscriber units. Thus, the local base station repeater cell transmits data directly to the individual subscriber units. The milliwatt transmitter individual subscriber units, however, do not transmit data directly back to the local base station repeater cell. Instead, the individual subscriber units transmit to a remote receiver which then relays the data to the local base station repeater cell. The use or remote receivers allows the individual subscriber units to transmit data using power in the milliwatt range.
Unfortunately, under certain conditions, individual subscriber units are unable to receive transmissions from the local base station repeater cell. For example, a user may purchase a subscriber unit and place the subscriber unit in an area which is not yet equipped with or is not covered by a local base station repeater cell. Additionally, a subscriber unit may be located within range of a local base station repeater cell, but may be positioned, for example, in a basement or other physical location which prevents the subscriber unit from receiving transmissions from the local base station repeater cell.
In an attempt to alleviate reception problems, local base station repeater cells have been situated with overlapping coverage to produce strong signals throughout a given area. However, such placement of local base station repeater cells is extremely costly due to the number of local base station repeater cells required, and such "crowded" placement of the local base station repeater cells is not always practical. In a further attempt to deal with ineffective communication between the local base station repeater cell and the subscriber unit, the location of the user is determined at the time of sale of the subscriber unit to the user. However, even if the user's location is within an area covered by the local base station repeater cell, the subscriber unit might still be placed in a physical location which prevents the subscriber unit from receiving signals from the local base station repeater cell.
Thus, the need has arisen for a system to enable communications between a subscriber unit and a local base station repeater cell in areas where such communication has previously been impaired, which does not require the addition of numerous costly local station repeater cells, which is not dependent on the physical location of the subscriber unit, and which does not significantly increase the cost of communication within the interactive two-way broadcast data service network.